Effects of ingestion of milk and methionine on blood levels of tryptophane and methionine in dairy calves

Series of blood samples were taken from Holstein calves before, and at 2, 4, and 6 hours after feeding. The blood plasma levels of tryptophane and methionine were determined by microbiological assay. It was found that the blood plasma levels of tryptophane and methionine varied considerably at different time intervals after feeding milk. One calf was fed 50 grams dl-methionine with its regular feed of milk, and series of blood samples were taken and assayed as in previous work. The methionine level increased to approximately 4 times its initial value by 2 hours after feeding, continued to rise, and at 6 hours after feeding was more than 10 times the original level. At the same time the tryptophane level showed a consistent decline. Determinations for total amino nitrogen were made, using a modification of the Folin-Wu method. The values obtained at different time intervals after feeding ranged from 6.45 to 9.33 mg./100 ml. blood. It was found that feeding methionine increased the blood level for total amino nitrogen, reaching a peak four hours after feeding. A special electrometric titration apparatus was used for making titrations. Approximately 1750 assays, consisting of standards and test samples, were titrated in this experiment.

Name thesis:degree_name

M.S.

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Dairy Husbandry

Department dc:contributor.department

Dairy Husbandry

Grantor dc:publisher

Virginia Polytechnic Institute

Year dc:date.issued

1949

Author dc:creator

• Engberson, Ray Dale

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10919/109850

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/109850